Polycarbonate-polyester copolymers are known in the art.
For example, Fox et al., U.S. Pat. Nos. 4,367,317 and 4,507,442, disclose copolymers prepared by the interaction of a melt mix of a high molecular weight bisphenol-A polycarbonate polymer, or a low molecular weight bisphenol-A polycarbonate polymer, and a high molecular weight diprimary dialcohol polyester polymer. The preferred polyester resin is polyethylene terephthalate.
Fox et al., U.S. Pat. No. 4,358,568, disclose copolymers prepared by the interaction of a melt mix of a polyarylate such as bisphenol A-isophthalate-terephthalate polyarylate, or bisphenol A-isophthalate-terephthalatecarbonate polyarylate and a high molecular weight diprimary dialcohol polyester polymer.
Fox et al., U.S. Pat. No. 4,510,289, disclose blends of polycarbonate and thermoplastic condensation polymers such as a co-polyestercarbonate, or a polyarylate, which are compatible in mixtures having varying ratios of components and which have improved properties.
Fox et al., U.S. Pat. No. 4,511,693, disclose blends of polycarbonate and thermoplastic addition polymers. The addition polymers used in the invention are comprised of units derived from repeat groups including a heterogroup.
Fox et al., U.S. Pat. No. 4,461,877, disclose thermoplastic compositions containing polycarbonate and poly(ethylene terephthalate) resins which are admixed to provide the composition with a single glass transition point (Tg).
Tyrell, U.S. Pat. No. 4,560,722, discloses thermoplastic compositions comprising di- and poly-ester resins and polycarbonate resins stabilized with boric acid.
Okamura et al., U.S. Pat. No. 3,218,372, disclose molding compositions comprising polycarbonates and polyalkylene terephthalates, e.g., poly(bisphenol-A carbonate and poly(ethylene terephthalate) whereby the two polymers are melt-mixed under a nitrogen atmosphere. Although the compositions are used for molding, they are merely melted together under nitrogen, e.g., at 290.degree. C., and they are not described to be copolymers, but merely a "uniform mixture".
Schade et al., U.S. Pat. Nos. 3,299,172 and 3,413,379, disclose processes for the preparation of linear thermoplastic mixed polyesters by reacting a diaryl arylate, a poly(alkylene arylate) and, optionally, a diaryl carbonate in the presence of a transesterification and polycondensation catalyst. The materials produced by these processes are described to be "mixed polyesters" and they are not copolymers containing poly(aryl carbonate) units, although isolated mono aryl carbonate linkages might be produced if a diaryl carbonate is included in the reaction mixture.
Mercier et al., U.K. Patent No. 1,569,296, disclose that mixing aromatic polyesters and aromatic polycarbonates in the molten state induces a reaction leading to fast degradation of the polymers, but if an acidic stabilizing additive is then added, a useful product can be obtained, but in which the polyester and the polycarbonate are only "partly copolymerized". The stabilizing additive serves to prevent further reaction and is, therefore, not a catalyst. All of the additives exemplified in U.K. '296 are acidic, such as a phosphorous compound or a carboxylic acid. Moreover, such compositions will have three glass transition temperatures, one each for the respective homopolymers, and one for the copolymer. In terms of ultimate physical properties and appearance, as well as environmental resistance, such compositions are deficient, especially in comparison with the compositions of the Fox et al. patent which have only a single glass transition temperature. Such compositions also tend to become yellow with time.
In co-pending commonly-owned application, Ser. No. 947,660 now U.S. Pat. No. 5,055,531 filed Dec. 30, 1986, there are disclosed copolymers prepared by the interaction of a melt mix of a high molecular weight polyester polymer, such as a poly(alkylene arylates) and a high molecular weight polycarbonate or polyester carbonate in the presence of a catalyst. The copolymers are characterized by having substantially no content of polyester homopolymer and a ratio of arylate linkages to dihydric phenol arylate linkages of not substantially less than 20:1.
It is also known that polyphenylene ether and polyester resins are normally incompatible with one another and can form effective blends only when compatibilized such as through the use of compatibilizers. Such compatibilizers include rubber-modified high-impact polystyrene and polycarbonate. Moreover, reinforcements and/or flame retardant additives can be added to those blends.
For example, Abolins et al., U.S. Pat. No. 4,013,613, disclose thermoplastic compositions which include admixtures of polyphenylene ether and polyester resins. Included within the thermoplastic compositions of the patentees are those wherein the admixtures of resins are in combination with a reinforcing amount of a reinforcing filler. In combination, the three-component thermoplastic compositions included within the invention are those which do not delaminate or separate when cooled, and those which do not manifest a failure to form structurally useful compositions because of reduced gross physical properties, chemical resistance, macroscopic appearance and the like.
Betts et al., EP-A 0133641, disclose flame retardant thermoplastic compositions of admixtures of a polyester resin and a flame retardant agent comprised of a combination of a polyphenylene ether resin, an organic phosphate and a stable brominated material.
Lee, U.S. Pat. No. 4,123,410, discloses a thermoplastic composition of an admixture comprised of polyphenylene ether, a plasticizer and an amount of a polyester sufficient to reduce the melt viscosity of said composition without substantially reducing the heat distortion temperature and ductility properties. The preferred amount of polyester is 2-5% by weight.
Also, Lee et al., U.S. Pat. No. 4,206,154, disclose self-extinguishing thermoplastic molding compositions comprising a polyphenylene ether resin, a styrene resin, a halogenated aromatic flame retardant, ferrocene and from 1-15% by weight of a fatty-acid terminated saturated polyester.
Also, in copending commonly-owned application, Ser. No. 891,457 filed Jul. 29, 1986, now abandoned there are disclosed highly compatible polymer blends having a high degree of impact resistance and solvent resistance. These blends comprise at least one polyphenylene ether or blend thereof with at least one one polystyrene, at least one poly(alkylene dicarboxylate), at least one elastomeric polyphenylene ether-compatible impact modifier, and at least one polymer containing a substantial proportion of aromatic polycarbonate units. Illustrative of the linear polyesters are the poly(alkylene dicarboxylates) and especially the poly(alkyleneterephthalates).
In copending, commonly owned application, Ser. No. 010,867 filed Feb. 4, 1987, now abandoned there are disclosed similar polymer blends which are highly compatible and have high solvent resistance and favorable tensile properties but which are particularly useful in applications where impact strength is not the primary consideration. Finally, Seiler et al., U.S. Pat. No. 4,672,086 disclose self-extinguishing thermoplastic polyester molding materials containing a linear aromatic polyester resin, a polyphenylene ether resin, a phosphate-containing compound and a filler. The compositions may optionally contain an aromatic polycarbonate.